Apparatus for cleaning windows



Jan. 10, 1967 M. SHORE APPARATUS FOR CLEANING wmnows 2 Sheets-Sheet 1 Filed Dec.

INVENTOR. MELVIN SHORE BY H d- H5- APPARATUS FOR CLEANING WINDOWS 2 Sheets-Sheet 2 ii gla Filed Dec. 5, 1963 INVENTQR, MELWN SHORE United States Patent f 3,296,645 APlARATUS FOR CLEANING WINDOWS Melvin Shore, 2720 W. Summer-dale, Chicago, Ill. 60625 Filed Dec. 5, I963, Ser. No. 329,609 2 Claims. (Cl. 15-220) This invention relates to window cleaning apparatus, and more particularly to window cleaning apparatus comprising magnetically coupled master and slave cleaning units for simultaneously cleaning opposite sides of a windowpane.

The subject matter of this application is disclosed in part in my co-pending application Serial No. 88,840, filed February 13, 1961.

Various attempts have been made in the past to develop window cleaning apparatus which would operate to simultaneously clean both the outside and the inside of a windowpane. Such apparatus is particularly useful for cleaning hard to reach portions of a window, such as upper corners or portions made inaccessible by the close proximity of storm windows or screens.

Various devices have in the past been suggested which utilize magnetic attraction. Typically, such devices have .included a first cleaning unit for positioning on one side of a windowpane and a second cleaning unit for positioning on the opposite side of the windowpane, with one or both cleaning units including magnetic members secured thereto to provide a magnetic circuit passing through the windowpane. The mutual magnetic attraction between the cleaning units thereby provided forces which retained both cleaning units against the respective windowpane surfaces. In theory, manual movement of the first cleaning unit (which for purposes of this specification will be referred to as the master unit) resulted in corresponding movement of the second cleaning unit (referred to herein as the slave unit). With appropriate cleaning means attached to each unit, both sides of the windowpane could thereby be simultaneously cleaned.

In order to be elfective and commercially practical, such window cleaning apparatus should possess certain qualities or characteristics. For example, it is desirable that the apparatus be simple and economical. It is also desirable that it operate effectively, both in terms of properly cleaning the window, and also in terms of main taining the slave unit in position during operation so that undue time and effort are not expended in repeatedly retrieving the slave unit. Further, it is desirable that the apparatus be compact so as to readily fit into limited spaces, such as between inner and outer windows or screens, and also be light in weight.

Prior devices have failed in one or more of the above respects. The prior devices which were simple and economical, as for example, the device shown in US. Patent No. 2,634,444, which utilizes a pair of simple bar magnets, lacks desired stability in operation, the slave unit having a strong tendency to uncouple from the master unit and to fall from the window. On the otherhand, other prior attempts which have provided sufficient holding power for ef ective operation, have generally involved auxiliary apparatus for obtaining same, which is cumbersome, complicated or expensive.

Accordingly, a primary object of the present invention is to provide improved magnetic window cleaning apparatus. A more specific object is the provision of such apparatus which comprises compact master and slave units. A further object is to provide magnetic window cleaning apparatus constructed so as to provide more effective holding power. More specifically it is an object to provide multi-directional holding power of a sustained force to give continuous contact during the operaazaasis Patented Jan. 10, 1967 ice tion of the apparatus. A further specific object is to provide magnetic window cleaning apparatus having substantially improved tracking capability. A further object is to provide magnetic window cleaning apparatus which is simple to construct and operate, durable, and also economical.

Various other objects and advantages of the present invention will become obvious from the following description and the associated drawings, in which:

FIGURE 1 is a generalized perspective view of magnetic window cleaning apparatus embodying features of the present invention in which the apparatus is shown in operating position on a household window;

FIGURE 2 is an enlarged perspective view (with parts broken away) of the apparatus shown in FIGURE 1, the master unit of the apparatus being shown in its operating position adjacent one surface of the windowpane, and the slave unit being shown on the other side of the windowpane and generally opposite the master unit, but positioned somewhat outwardly from its operating position so as to show its structure more clearly;

FIGURE 3 is a side sectional view of the apparatus shown in FIGURES 1 and 2;

FIGURES 4 is a plan view of the inner surface of one unit of a second embodiment of the window cleaning apparatus of the present invention;

FIGURE 5 is a perspective view of molten material being poured into a mold to produce the window cleaning apparatus of the present invention;

FIGURE 6a is a plan view, partly broken away, of a master unit constructed similarly to the unit illustrated in FIGURE 4, but including certain additional features of the present invention;

FIGURE 6b is a side cross-sectional view of the master unit of FIGURE 6a;

FIGURES 7a, 7b, 8a and 8b are schematic perspective views of various arrangements of magnetic members which, in conjunction with the following description, will facilitate an understanding of one of the features of the present invention; and

FIGURE 9 is a schematic plan view of the inner surface of a third embodiment of the window cleaning apparatus of the present invention.

Very briefly, with reference to the drawings, the window cleaning apparatus 10 of the present invention comprises a pair of self-contained magnetic cleaning units 12 including a master cleaning unit and a slave cleaning unit 12d, which are adapted to be positioned on either side of a windowpane 14 opposite one another. When the master unit 120 is moved about on its side of the windowpane 14, the slave unit 12d is thereby moved along substantially the same path, but on its opposing side of the windowpane 14. Thus, both sides of the windowpane 14 are cleaned or polished simultaneously, and in addition, the slave unit 12d can be readily moved to hard-to-reach points on the side of the windowpane opposite the user.

An important feature of the present invention is the particular disposition of magnetic elements in the master and slave units, which provides substantially improved performance and operation in comparison with magnetic window cleaning apparatus heretofore known. In this connection, a serious problem encountered in prior art devices has been a pronounced tendency for the slave unit to become uncoupled from the master unit if the master unit is moved suddenly or erratically across the surface of the windowpane; if the slave unit encounters a surface irregularity on its side of the windowpane; if the slave unit encounters a region of high friction on its surface of the windowpane; or, for that matter, if anything occurs which disrupts the inertia of the slave unit or causes substantial drag on the slave unit. Once the magnetic couple between the master and slave units is lost, the slave unit naturally falls from the windowpane, necessitating its retrieval and repositioning. The frequency with which the slave unit of prior art devices has uncoupled has made such devices unattractive, if not impracticable, in most potential applications for such devices.

In accordance with the present invention, however, the tendency of the slave unit to become uncoupled is substantially reduced, to the extent that it is thereby entirely feasible to utilize the apparatus of the present invention under all ordinary conditions.

In this connection, and with particular reference to FIGURES 2 and 3 of the drawing, it will be seen that, secured to both the master cleaning unit 120 and the slave cleaning unit 12d, is a plurality of magnetic elements 20. The magnetic elements 20 are adjacently disposed and are polarized in a direction perpendicular to the plane of the windowpane, with adjacent magnetic elements 20 presenting to the windowpane pole faces of opposite polarity. The pole faces of the magnetic elements 20 which are presented to the windowpane will sometimes be referred to herein as inner pole faces. The magnetic elements 20 of the master cleaning unit 120 and of the slave cleaning unit 12:! are also arranged so that in operating position the inner pole faces on the master cleaning unit 12c are aligned with inner pole faces of unlike polarity on the slave cleaning unit 12d.

It has been found that the arrangement of magnetic elements 20 illustrated in FIGURES 2 and 3, or equivalent arrangements of magnetic elements, provide substantially improved results in comparison with prior magnetic window cleaning devices. In this connection, the attractive magnetic forces existing between the master cleaning unit 12c and the slave cleaning unit 12d when the units are disposed on a windowpane in their operating position can be resolved into two sets of component forces.

The first set of forces operates perpendicular to the plane of the windowpane, and these forces urge the respective cleaning units toward each other and against the windowpane surfaces. Forces comprising this first set are referred to herein as coupling forces. The second set of forces operates parallel to the plane of the windowpane, and these forces are the only forces which act upon the slave cleaning unit 12a to cause it to track the master cleaning unit as the latter is moved over the surface of the windowpane in the usual paths used in cleaning a window. Forces comprising this second set are referred to herein as tracking forces.

I have found that, in order to provide a magnetic window cleaning apparatus which is commercially practical, not only should there be coupling forces of sufficient magnitude to provide desired cleaning ability, but there should also be tracking forces of commensurate magnitude. The apparatus of the present invention provides the necessary tracking forces, which prior magnetic cleaning devices have not.

In this connection, and with reference to FIGURES 7a, 7b, 8a, and 8b of the drawing, testing apparatus was set up whereby the relative tracking forces between various arrangements of magnetic elements was determined. The testing apparatus comprised a horizontally disposed separator 11 of non-magnetic material about A" in thickness, which had a magnetic permeability approximately the same as that of window glass. Small square magnets 13 were provided, which were about /1 long on each side and had a thickness of about & Each magnet 13 was polarized in the direction of its thickness.

The magnets 13 were clamped together in sets of the various combinations illustrated, and were placed with one set on the top surface of the separator 11 and another magnetically complementary set on the bottom surface of the separator 11, so that the sets were magnetically coupled through the separator 11. One end of a steel spring was then secured to the set on the top surface of the separator 11, and the other end of the spring was affixed to a pin 17 on the separator.

Thereupon, the bottom set of magnets 13 (master unit) was manually moved along the bottom surface of the separator 11 in the direction indicated by arrow L, so

that the tracking forces between the top and bottom sets of magnets were opposed by the spring 15. The bottom 5 set of magnets was moved until the top set of magnets 13 (slave unit) became uncoupled from the bottom set and the net displacement of the top set against the tension of the spring 15 along the path L was measured (Test No. 1). This net displacement was directly proportional to the tracking forces between the sets, since the elastic limit of the spring 15 was never exceeded.

Both sets of magnets were then rotated 90, and the net displacement was again measured, using the same spring 15 (Test No. 2). For convenience of illustration, this has been shown in FIGURES 7a, 7b, 8a, and 8b as displacement in the direction of the arrow L'.

In FIGURE 7a, each set of magnets comprised two magnets 13 in side-by-side relation, with the magnets in each set presenting only S pole faces or only N pole faces to their respective surfaces of the separator 11.

In FIGURE 7b, each set again comprised two magnets 13 in side-by-side relationship, but with the magnets in each set presenting a S and a N pole face to their respective surfaces of the separator 11.

In FIGURE 8a, each set of magnets comprised four magnets 13 in side-by-side relation, with the magnets in each set presenting only S pole faces or only N pole faces to their respective surfaces of the separator 11.

In FIGURE 8b, each set of magnets again comprised four magnets 13 in side-by-side relationship but with adjacent magnets presenting pole faces of opposite polarity to their respective surfaces of the separator 11.

The same procedure described in connection with FIG- URE 7a was repeated for the magnet arrangements shown in FIGURES 7b, (Tests Nos. 3 and 4) 8a, (Tests Nos. 3 and 4) 8a, (Tests Nos. 5 and 6) and 8b, (Tests Nos. 7 and 8) and the net displacements of the top set against the tension of the spring 15 in the directions of arrows L and L thereby obtained. Table I sets forth all the foregoing measured displacements.

Table 1 Test No. Magnet Direction of Not Displace- Arrangement Displncmnent meut Inches Figure 7a L 3. I) Figure 7a l. 0 '3 Figure 7b l. 5 4 Figure 7b. 4.5 5 I Figure 8a. L 2. 25 6 Figure 8a. 2. 25 7 Figure 8h 7. 25 8 Figure 8b- 7. 25

It will be seen from the foreging that the magnet arrangement shown in FIGURE 8b, which is equivalent to the arrangement of the magnetic elements 20 in FIG- URES 2 and 3, provides tracking forces having a magnitude more than three times greater than the arrangement shown in FIGURE 8a. It will also be seen that the magnet arrangement shown in FIGURE 7b, while providing tracking forces having a magnitude more than four times greater than the arrangement shown in FIGURE 7a in direction L, does not provide substantially improved tracking forces in direction L, as measured by this test procedure. Since, to provide the improved results of the present invention the slave unit should track the mas ter unit in all paths through which it may be moved, the magnet arrangement of FIGURE 7b is not satisfactory for purposes of the present invention. On the other hand, the arrangement of magnetic elements in FIGURE 8b, comprising two pairs of adjacent inner pole faces of opposite polarity, does provide the benefits of the present invention. The pairs are spaced apart in directions which make an angle with respect to each other of about 90.

In this connection, with respect to the disposition of magnetic elements which does provide the substantially improved tracking forces between the master and slave units in accordance with the present invention, the magnetic elements in each of the units are disposed so that transverse displacement of the master unit in any direction relative to the slave unit tends to align an inner pole face on the master unit with an inner pole face of like polarity of the slave unit. Stated differently, the magnetic elements in each unit are disposed with adjacent elements presenting to the windowpane pole faces of opposite polarity with the path of a pole face in each unit being at least partially overlapped by a path of a pole face of opposite polarity in all paths through which the unit can be moved in the plane of the windowpane.

The foregoing requirement is met by the various em bodinients of cleaning units illustrated in FIGURES 2, 3, 4, Sb and 9, and provide substantially improved tracking forces in comparison with prior magnetic window cleaning devices.

The tracking forces between the master and slave units may be further increased by the provision of a magnetically conducting member across the outer pole faces of the magnetic elements of each unit. In this connection, and with reference to FIGURES 8a and 8b of the drawing, additional tests were conducted wherein sheets of galvanized iron Were clamped to the top and bottom sets of magnets 13 against the outer pole faces of each set. The net displacements of the top set against the force of the spring were measured, and these displacements are set forth in Table II. (Tests Nos. 9 and 10).

Also set forth in Table II is the result of Test No. 11 wherein the top set of magnets of FIGURE 8!) was replaced by a non-polarized piece of iron having about the same dimensions as the set of magnets, and its displacement against the force of the spring was measured.

It will be seen from Table II that the provision of the sheet iron resulted in substantially increased tracking forces in both cases, but that the tracking forces provided by the arrangement illustrated in FIGURE 8b were still substantially greater than those provided by the arrangement illustrated in FIGURE 8a. It will also be seen that the provision of a non-polarized element as a slave unit instead of the polarized set does not provide the benefits of the present invention.

It has been found, in accordance with the present invention, that the magnetic elements in each unit are desirably disposed closely adjacent one another. Preferably, however, they are not disposed in abutting relationship, but are slightly separated from each other, either by an air gap or 'by other magnetically insulating material. In addition, the magnetic elements desirably are spaced from each other by a distance less than the average diameter or width of the elements, and preferably are spaced from each other by a distance less than about half the average width or diameter of the elements. More remote spacing of the elements results in a substantial decrease in the tracking forces between the master unit and the slave unit.

Referring now to FIGURE 1 of the drawing, the magnetic window cleaning apparatus 10 of the present invention embodies the described features to provide desired coupling and tracking forces between the master cleaning unit 120 and the slave cleaning unit 12d. These forces are maintained even when the master cleaning unit 120 is moved suddenly, rapidly, or in any direction, and also despite jarring of the slave cleaning unit 12d against the window frame 16.

While the units may be of other shapes, sizes, and

configurations, the illustrated units 12 have a rectangular shape which provides square corners for getting into the square corners of windows to clean them. The illustrated units 12 each include a frame 18 and magnetic elements 29 which are secured to the frame. As will become clearer as the description proceeds, the dimensions ofthe units 12 are not directly dependent upon the dimensions of the configuration formed by the magnetic elements 20, except that the units should not be so disproportionately large or heavy that the elements will be unable to operate the unit in the desired manner. Examples of such modifications are shown in FIGURES 4 and 9 to be described in more detail below, in which the units are rectangular while the elements form circular or ring-shaped configurations.

Then also, the size and configuration of the master and slave units 12c and 12d need not be the same. It may be desirable in a particular embodiment that the size of the manually operable, master unit 12c be larger than that of the slave unit 12d. Since the slave unit 12d must be maintained by magnetic force, it is usually desirable to minimize its weight (within the limits of effective operation), but as the master unit 12c is supported by the user, its weight does not present the same problem, and it may be made thicker to facilitate its being easily grasped. This will also increase the magnetic coupling forces exerted between the units 12. However, the mastcr unit and the slave unit 12d of the illustrated apparatus 10 are generally similar, for while, as has been pointed out, it is not necessary that they be alike, making them alike does eliminate the necessity for designing and manufacturing different parts for each unit. In addition, it enables the two illustrated units to be used interchangably, i.e., either may be used as the master unit, while the other serves as the slave unit.

It being understood that a number of constructions for producing such a cleaner are available, the particular structure of apparatus shown in the drawings will now be described. The slave unit 120. will be described, it being also understood that what is said will generally also apply to the master unit 120.

As seen best in FIGURES 2 and 3, the frame 18 of the illustrated slave unit 12d is a flat rectangular block preferably made from a non-magnetic material such as rubber, wood or certain suitable plastics. The frame 18 has a rectangular center opening or cavity 22 extending through it, in which are received a plurality of small rectangular, permanently polarized magnetic elements 28 of a magnetic material such as ceramic or steel. The illustrated elements 20 are separate magnets.

However, it is also possible to polarize a single large sheet of magnetic material in a plurality of regions to provide an equivalent structure. As used herein, magnetic element is intended to include such polarized regions in a single sheet.

The illustrated elements 20 are disposed side-by-side in the opening 22 and are arranged in adjacent rows so as to form a flat, rectangular configuration which substantially fills that rectangular opening 22. They may be secured to the frame 18 in any suitable manner so long as the proper magnetic relationships of the apparatus are not disturbed.

As seen best in FIGURES 2 and 3, each magnetic element 24] of each unit 12c and 12d is polarized in 21 direction perpendicular to the plane of the windowpane.

In the illustrated slave unit 12d, the magnetic elements 24 are arranged in checkerboard fashion with regard to the polarity of their inner pole faces; i.e., adjacent magnetic elements have inner pole faces of opposite polarity. The magnetic elements Ztl on the master unit 120 are also arranged in a checkerboard fashion, so that, when the units are in their operating position, corresponding or mating opposed elements are in alignment with one another. However, the polarities of the inner pole faces of the magnetic elements 20 of unit 12c are opposite those of the inner polarities of the corresponding inner pole faces of unit 12d. As opposite polarity attracts, opposed pairs of elements exert a magnetic attraction upon one another, and the units 12 are drawn together and against the opposite sides of the windowpane 14.

The pair of checkerboard configurations, each having a number of relatively small elements 20, provide magnetic attraction of improved characteristics over that provided by prior magnetic window cleaning devices as previously pointed out. Of particular importance is the multi-directional quality of the attraction provided, i.e., attraction such as will cause the slave unit to track in all directions and not just in one or a few directions. Also of importance is the steady, constant quality of the attraction which enables the apparatus to effectively perform its cleaning function without skipping.

Secured to one side of the illustrated frame 18 is a connection member 24 which is made of a magnetic material, and in the illustrated device is a rectangular plate of material such as galvanized iron. This connection member 24 contacts the outer pole faces of the magnetic elements 20 and serves as a connection or bridge for magnetic flux or lines of force between adjacent elements acting as noted above, to enhance the magnetic forces between the units. The magnetic attraction between the member 24 and the magnetic elements 20 on each unit also assists in holding the parts of the unit together and in proper relative alignment.

In the illustrated slave unit 12d, separators 25, made 'of non-magnetic material such as that used for the frame 18, are disposed between adjacent elements 29 and serve to separate them from one another. These separators improve the magnetic functioning of the illustrated apparatus 10, possibly because they serve to reduce leakage flux between adjacent magnetic elements 2t) on the same unit which would otherwise short-circuit the desired circuit through the windowpane. It is also possible that they tend to reduce any neutralizing action between magnetic elements 20 by separating elements of like polarity at the corners where they would otherwise come together. The separators 25 may be an integral part of the frame 18, or there may be a number of pieces secured in place by any suitable means such as adhesive.

In the illustrated apparatus 10, the surface of the unit 12d which is adapted to lie adjacent the windowpane 14 when the apparatus is being used, is made generally fiat and smooth by making the inner pole faces of the magnetic elements 20 generally flush with the adjacent inner face of the frame 18. A cleaning means 23 is supported on the unit 12d upon this flat surface by any suitable attaching means and is urged against the windowpane 14 by virtue of the magnetic force urging the unit 12d toward the windowpane. The cleaning means 23 is desirable removably attached so that it may be cleaned or replaced as needed. In addition to possessing the necessary cleaning characteristics, such as being relatively lint free, it is desirable that the cleaning means '23 be relatively thin so as to minimize the separation lbetween the units 12. It also should provide low fricttion contact with the window and a minimum of irregularities so as not to interfere with the proper operation of the device. A thin, smooth cloth sack or bag which fits over the unit and may have an elastic around its open end to maintain it upon the unit, as shown in FIGURE 2, has proved satisfactory as a cleaning means 23. In addition, the illustrated unit 12d has a thin concentrator 'pad 30 which is attached to its inner face and has substantially less surface area than that inner face. The concentrator pad 30 is fabricated from wood, fibreboard, plastic or other non-magnetic material. The particular illustrated pad is a generally ring-shaped disk. This pad 30 will serve to concentrate and intensify the pressure exerted by the unit 12d upon the windowpane by reducing the area of contact between the unit 12?!" and ;the windowpane to increase the per unit area force.

This is desirable for certain cleaning operations. As illustrated in FIGURE 3, a concentrator pad 30 may also be attached to the inner face of unit 12c, if desired, so that either unit 12c or unit 12d may be used as the remote unit. The pad also will tend to reduce vibration of the slave unit, making for smoother operation. The pad 30 should be sufliciently thin so that the reduction in total attraction caused by the further spacing apart of of the units is more than offset by the concentrating action of the pad. An elongated chain or cord 26 may be provided which is fixed at either end to the units 12c and 12d to limit the fall of the slave unit 12d if it should become disengaged from its magnetic connection with the master unit 120. This is primarily a safety measure, but in addition it eliminates the job of retrieving the slave unit 12d if it should fall any considerable distance.

One convenient and novel method of fabricating a window cleaner unit of the type described is partially depicted in FIGURE 5. The method includes locating the magnetic elements 28 on the connection member or plate 24 with each of the elements having one of its pole faces adjacent the plate and the opposed pole face away from it, and placing the plate and the elements in a mold 28. For a structure such as the one shown in FIG- URES 1 to 3 which incorporates separators between the magnetic elements 20, the elements should be located on the plate in the appropriate adjacently spaced-apart relation to one another. A quantity of molten material, such as rubber, which will harden at normal atmospheric temperatures, is poured into the mold so as to fill the spaces between elements and reach a height substantially level with the plane of the pole faces of the elements which are away from the plate. The molten material is allowed to solidify to provide the frame 18 of the unit. This is a particularly simple yet effective way to produce separators 25 between the elements 20, as the molten material will run between the elements, filling any spaces and forming the rather intricate frame as a single integral part, with a minimum of effort and expense.

FIGURE 4 shows a modification of the structure shown in FIGURES 1 through 3. In the latter figure, the same number will be used to designate corresponding parts, but they will be given the sufiix a. The magnetic window cleaning apparauts 10a has a frame 18a of rectangular construction generally similar to that of frame 18. In apparatus 10a, however, the magnetic elements 20a are constructed and arranged to provide a ring-shaped structure rather than the general rectangular magnetic structure of the principal embodiment. As can be seen in FIGURE 4, the illustrated magnetic elements 20a are partial, pie-shaped segments which are arranged sideby-side to form the ring or circular washer shaped magnetic structure. This modified structure presents a number of magnetic elements 20a positioned adjacent elements of opposite polarity without also having portions of elements of the same polarity positioned close together as in the principal embodiment. This reduces any neutralizing effect and reduces the necessity of separators such as the separators 25 of the principal embodiment.

In FIGURES 6a and 62'), there is illustrated a magnetic Window cleaning apparatus 10c which includes magnetic elements 2% arranged identically to the arrangement of FIGURE 4. There is illustrated only a master unit 12b, it being understood that the slave unit has magnetic elements disposed substantially identical to the master unit.

It will be seen from FIGURE 6!) that the magnetic elements 201) are attached to an annular plate 24b. The plate 24b is fabricated from a magnetic material such as steel. The unit 12b is constructed so that the magnetic elements 20!) may be selectively moved closer to or further from the windowpane.

In this connection, the unit 1215 includes a frame 181) fabricated from a non-magnetic material. In the illustrated embodiment, a stud 32 is embedded in the frame 18b centrally on the frame. The annular plate 2% is disposed around the stud 32, which stud extends through the annulus of the plate. A nut 34 is provided which engages the threads of the stud 32, against which the plate 24b is biased by a spring 36.

A handle 38 is attached to the frame 18b to facilitate operation of the unit.

The apparatus illustrated in FIGURES 6a and 61) enables desirable operation on windowpanes of varying thickness. In this connection, the narrower the gap between the master unit and the slave unit, the less magnetic force is required between the two units for desirable operation. However, if the placement of the magnetic elements in the units is chosen for desirable operation on a double-thickness windowpane, the same gap =may provide excessive coupling forces for desirable ope-ration on a single-thickness windowpane. By means of the embodiment illustrated in FIGURES 6a and 6b, the gap may be selected to provide optimum results on various thicknesses.

In FIGURE 9, there is illustrated a third arrangement of magnetic elements which provides the benefits of the present invention. It will be seen that one of the elements comprises an annular magnetic element 20c, within the annulus of which is disposed a circular magnetic element 20d. The inner pole faces of the elements 200 and 20d have opposite polarities, and master and slave units comprising this arrangement also provide substantially improved tracking forces in comparison with prior magnetic window cleaning devices.

It will be noted that the embodiment of FIGURE 9 differs from the previously-described embodiments wherein the paired inner poles faces of the magnetic elements comprise discreet areas. However, the arrangement of the magnetic elements 200 and 20d of FIG- URE 9 is structurally equivalent thereto if it is consedired that the annular element 200 comprises an infinite number of wedge-shaped areas of one polarity positioned adjacent an infinite number of pie-shaped areas of opposite polarity on the circular element 20d.

A particular feature of the disclosed embodiments is that the master unit and the slave unit will mate with each other in more than one relative position. For example, the arrangement of elements shown in FIGURE 2 enables mating of the units on opposite sides of a windowpane in four orthogonally-related positions; as does the arrangement shown in FIGURE 4. The arrangement shown in FIGURE 9 enables mating of the units in an infinite number of positions centered on the axes of the units.

Various changes and modifications, in addition to those already suggested, may be made in the disclosed structure without departing from the scope of the invention as set forth in the claims.

Various features of the invenion are set forth in the claims.

What is claimed is:

1. Magnetic window cleaning apparatus comprising a pair of self-contained magnetic units adapted to be positioned on either side of a windowpane opposite one another for remote-control cleaning of one of the Window surfaces, each of said units comprising a frame, multiple generally rectangular magnetic elements secured to said frame, a connecting plate for magnetically connecting together said magnetic elements, each of said magnetic elements of each of said two units being oriented so that when the apparatus is in operating position one of the poles of that element is positioned adjacent the windowpane to provide an inner pole face, and the other pole of that element is positioned away from the windowpane to provide an outer pole face, said connecting plate engaging the outer poles of said elements to magnetically connect them together, the generally rectangular magnetic elements of one of said units being oriented and arranged with their inner pole faces in a checkerboard-type alignment, whereby inner pole faces of one polarity lie adjacent to inner pole faces of the opposite polarity, the magnetic elements of the other unit being oriented and arranged so that when the apparatus is in operating position the inner pole faces of these elements have polarities opposite to those of the inner pole faces, respectively, of the magnetic elements of said first unit which are positioned opposite from them, means separating said adjacently disposed elements to reduce any neutralizing effect at the corners of said elements, whereby when the apparatus is operated each of the magnetic elements is located opposite from an element of opposite polarity and the resultant structure provides substantially sustained multi-directional magnetic connection between the units, and window cleaning means attached to one of said units.

2. Magnetic window cleaning apparatus comprising a pair of self-contained magnetic units adapted to be positioned on either side of a windowpane opposite one another for remote-control cleaning of one of the window surfaces, one of said units being a master unit and the other of said units being a slave unit which is adapted to follow the movements of said master unit, each of said units comprising a frame and a magnetic element secured to said frame, each of said magnetic elements being oriented so that when the apparatus is in ope-rating position one of the poles of the element is positioned adjacent the windowpane to provide an inner pole face, and the other pole of the element is positioned away from said windowpane to provide an outer pole face, the inner poles of said magnetic elements being of opposite polarity, whereby when the apparatus is operated said magnetic elements exert a magnetic attraction upon each other providing a substantially sustained and multi-directional connection between the units, said slave unit having a thin concentrator pad upon that surface of said slave unit which is located adjacent to the windowpane when the apparatus is in operating position, said concentrator pad being of substantially less surface area than said surface so as to reduce the area of contact between said slave unit and the windowpane, and window cleaning means attached to said slave unit outside said concentrator pad, so that when the apparatus is in operating position said window cleaning means lies between said concentrator pad and the windowpane.

References Cited by the Examiner UNITED STATES PATENTS 2,507,559 5/1950 DAndrea 152=20.1 2,805,438 9/1957 Hogensen 15- 2201 2,827,651 3/1958 Rizk 15210 2,896,043 7/1959 Andrews 200-8743 2,902,721 9/1959 Heuer 1859 2,903,329 9/1959 Weber 31-7201 X 2,958,019 10/ 1960 Sholten et a1 317201 X 2,972,784 2/ 1961 Shonka et al. 1859 FOREIGN PATENTS 1,182,981 1/ 1959 France.

856,978 12/1960 Great Britain.

888,344 1/ 1962 Great Britain.

CHARLES A. WILLMUTH, Primary Examiner.

WALTER A. SCHEEL, L. G. MACHLIN,

Assistant Examiners. 

1. MAGNETIC WINDOW CLEANING APPARATUS COMPRISING A PAIR OF SELF-CONTAINED MAGNETIC UNITS ADAPTED TO BE POSITIONED ON EITHER SIDE OF A WINDOWPANE OPPOSITE ONE ANOTHER FOR REMOTE-CONTROL CLEANING OF ONE OF THE WINDOW SURFACES, EACH OF SAID UNITS COMPRISING A FRAME, MULTIPLE GENERALLY RECTANGULAR MAGNETIC ELEMENTS SECURED TO SAID FRAME, A CONNECTING PLATE FOR MAGNETICALLY CONNECTING TOGETHER SAID MAGNETIC ELEMENTS, EACH OF SAID MAGNETIC ELEMENTS OF EACH OF SAID TWO UNITS BEING ORIENTED SO THAT WHEN THE APPARATUS IS IN OPERATING POSITION ONE OF THE POLES OF THAT ELEMENT IS POSITIONED ADJACENT THE WINDOWPANE TO PROVIDE AN INNER POLE FACE, AND THE OTHER POLE OF THAT ELEMENT IS POSITIONED AWAY FROM THE WINDOWPANE TO PROVIDE AN OUTER POLE FACE, SAID CONNECTING PLATE ENGAGING THE OUTER POLES OF SAID ELEMENTS TO MAGNETICALLY CONNECT THEM TOGETHER, THE GENERALLY RECTANGULAR MAGNETIC ELEMENTS OF ONE OF SAID UNITS BEING ORIENTED AND ARRANGED WITH THEIR INNER POLE FACES IN A CHECKERBOARD-TYPE ALIGNMENT, WHEREBY INNER POLE FACES OF ONE POLARITY LIE ADJACENT TO INNER POLE FACES OF THE OPPOSITE POLARITY, THE MAGNETIC ELEMENTS OF THE OTHER UNIT BEING ORIENTED AND ARRANGED SO THAT WHEN THE APPARATUS IS IN OPERATING POSITION THE INNER POLE FACES OF THESE ELEMENTS HAVE POLARITIES OPPOSITE TO THOSE OF THE INNER POLE FACES, RESPECTIVELY, OF THE MAGNETIC ELEMENTS OF SAID FIRST UNIT WHICH ARE POSITIONED OPPOSITE FROM THEM, MEANS SEPARATING SAID ADJACENTLY DISPOSED ELEMENTS TO REDUCE ANY NEUTRALIZING EFFECT AT THE CORNERS OF SAID ELEMENTS, WHEREBY WHEN THE APPARATUS IS OPERATED EACH OF THE MAGNETIC ELEMENTS IS LOCATED OPPOSITE FROM AN ELEMENT OF OPPOSITE POLARITY AND THE RESULTANT STRUCTURE PROVIDES SUBSTANTIALLY SUSTAINED MULTI-DIRECTIONAL MAGNETIC CONNECTION BETWEEN THE UNITS, AND WINDOW CLEANING MEANS ATTACHED TO ONE OF SAID UNITS. 